A satirical definition that, according to Steven Pinker, was "the common definition [in the Soviet Union] of the two Cold War ideologies". Pinker, Steven, The Better Angels of Our Nature: Why Violence Has Declined (N.Y.: Viking, hardback 2011 (ISBN 978-0-670-02295-3)), p. 634

Porphyry of Tyre, in "The Life of Pythagoras" as translated by Kenneth Sylvan Guthrie in The Pythagorean Sourcebook and Library: An Anthology of Ancient Writings which Relate to Pythagoras and Pythagorean Philosophy (1919); also quoted in The Golden Chain: An Anthology of Pythagorean and Platonic Philosophy (2004) by Algis Uzdavinys